Having a semaphore in there causes modest performance regressions on heavily
mmap-intensive workloads on some hardware.  Specifically, up to 30% in SDET on
NUMAQ and big PPC64.

So switch it back to being a spinlock.  This does mean that unmap_vmas() needs
to be told whether or not it is allowed to schedule away; that's simple to do
via the zap_details structure.

This change means that there will be high scheuling latencies when someone
truncates a large file which is currently mmapped, but nobody does that
anyway.  The scheduling points in unmap_vmas() are mainly for munmap() and
exit(), and they still will work OK for that.

From: Hugh Dickins <hugh@veritas.com>

  Sorry, my premature optimizations (trying to pass down NULL zap_details
  except when needed) have caught you out doubly: unmap_mapping_range_list was
  NULLing the details even though atomic was set; and if it hadn't, then
  zap_pte_range would have missed free_swap_and_cache and pte_clear when pte
  not present.  Moved the optimization into zap_pte_range itself.  Plus
  massive documentation update.

From: Hugh Dickins <hugh@veritas.com>

  Here's a second patch to add to the first: mremap's cows can't come home
  without releasing the i_mmap_lock, better move the whole "Subtle point"
  locking from move_vma into move_page_tables.  And it's possible for the file
  that was behind an anonymous page to be truncated while we drop that lock,
  don't want to abort mremap because of VM_FAULT_SIGBUS.

  (Eek, should we be checking do_swap_page of a vm_file area against the
  truncate_count sequence?  Technically yes, but I doubt we need bother.)


- We cannot hold i_mmap_lock across move_one_page() because
  move_one_page() needs to perform __GFP_WAIT allocations of pagetable pages.

- Move the cond_resched() out so we test it once per page rather than only
  when move_one_page() returns -EAGAIN.

From: Hugh Dickins <hugh@veritas.com>

Delete include/asm*/rmap.h
Delete pte_addr_t typedef from include/asm*/pgtable.h
Delete KM_PTE2 from subset of include/asm*/kmap_types.h
Beware when 4G/4G returns to -mm: i386 may need KM_FILLER for 8K stack.

From: Hugh Dickins <hugh@veritas.com>

Remove the support for pte_chain rmap from page table initialization, just
continue to maintain nr_page_table_pages (but only for user page tables -
it also counted vmalloc page tables before, little need, and I'm unsure if
per-cpu stats are safe early enough on all arches).  mm/memory.c is the
only core file affected.

But ppc and ppc64 have found the old rmap page table initialization useful
to support their ptep_test_and_clear_young: so transfer rmap's
initialization to them (even on kernel page tables?  well, okay).

From: Hugh Dickins <hugh@veritas.com>

A weakness of the anonmm scheme is its difficulty in tracking pages shared
between two or more mms (one being an ancestor of the other), when mremap has
been used to move a range of pages in one of those mms.  mremap move is not
very common anyway, and it's more often used on a page range exclusive to the
mm; but uncommon though it may be, we must not allow unlocked pages to become
unswappable.

This patch follows Linus' suggestion, simply to take a private copy of the
page in such a case: early C-O-W.  My previous implementation was daft with
respect to pages currently on swap: it insisted on swapping them in to copy
them.  No need for that: just take the copy when a page is brought in from
swap, and its intended address is found to clash with what rmap has already
noted.

If do_swap_page has to make this copy in the mremap moved case (simply a call
to do_wp_page), might as well do so also in the case when it's a write access
but the page not exclusive, it's always seemed a little odd that swapin needed
a second fault for that.  A bug even: get_user_pages force imagines that a
single call to handle_mm_fault must break C-O-W.  Another bugfix: swapoff's
unuse_process didn't check is_vm_hugetlb_page.

Andrea's anon_vma has no such problem with mremap moved pages, handling them
with elegant use of vm_pgoff - though at some cost to vma merging.  How
important is it to handle them efficiently?  For now there's a msg
printk(KERN_WARNING "%s: mremap moved %d cows\n", current->comm, cows);

From: Hugh Dickins <hugh@veritas.com>

Hugh's anonmm object-based reverse mapping scheme for anonymous pages.  We
have not yet decided whether to adopt this scheme, or Andrea's more advanced
anon_vma scheme.  anonmm is easier for me to merge quickly, to replace the
pte_chain rmap taken out in the previous patch; a patch to install Andrea's
anon_vma will follow in due course.

Why build up and tear down chains of pte pointers for anonymous pages, when a
page can only appear at one particular address, in a restricted group of mms
that might share it?  (Except: see next patch on mremap.)

Introduce struct anonmm per mm to track anonymous pages, all forks from one
exec sharing the same bundle of linked anonmms.  Anonymous pages originate in
one mm, but may be forked into another mm of the bundle later on.  Callouts
from fork.c to allocate, dup and exit the anonmm structure private to rmap.c.

From: Hugh Dickins <hugh@veritas.com>

  Two concurrent exits (of the last two mms sharing the anonhd).  First
  exit_rmap brings anonhd->count down to 2, gets preempted (at the
  spin_unlock) by second, which brings anonhd->count down to 1, sees it's 1
  and frees the anonhd (without making any change to anonhd->count itself),
  cpu goes on to do something new which reallocates the old anonhd as a new
  struct anonmm (probably not a head, in which case count will start at 1),
  first resumes after the spin_unlock and sees anonhd->count 1, frees "anonhd"
  again, it's used for something else, a later exit_rmap list_del finds list
  corrupt.

From: Hugh Dickins <hugh@veritas.com>

Lots of deletions: the next patch will put in the new anon rmap, which
should look clearer if first we remove all of the old pte-pointer-based
rmap from the core in this patch - which therefore leaves anonymous rmap
totally disabled, anon pages locked in memory until process frees them.

Leave arch files (and page table rmap) untouched for now, clean them up in
a later batch.  A few constructive changes amidst all the deletions:

Choose names (e.g.  page_add_anon_rmap) and args (e.g.  no more pteps) now
so we need not revisit so many files in the next patch.  Inline function
page_dup_rmap for fork's copy_page_range, simply bumps mapcount under lock.
 cond_resched_lock in copy_page_range.  Struct page rearranged: no pte
union, just mapcount moved next to atomic count, so two ints can occupy one
long on 64-bit; i386 struct page now 32 bytes even with PAE.  Never pass
PageReserved to page_remove_rmap, only do_wp_page did so.


From: Hugh Dickins <hugh@veritas.com>

  Move page_add_anon_rmap's BUG_ON(page_mapping(page)) inside the rmap_lock
  (well, might as well just check mapping if !mapcount then): if this page is
  being mapped or unmapped on another cpu at the same time, page_mapping's
  PageAnon(page) and page->mapping are volatile.

  But page_mapping(page) is used more widely: I've a nasty feeling that
  clear_page_anon, page_add_anon_rmap and/or page_mapping need barriers added
  (also in 2.6.6 itself),

Many places do:

	if (kmem_cache_create(...) == NULL)
		panic(...);

We can consolidate all that by passing another flag to kmem_cache_create()
which says "panic if it doesn't work".

From: Hugh Dickins <hugh@veritas.com>

The previous patch let the ptes of file pages be located via page
->mapping->i_mmap and i_mmap_shared lists of vmas; which works well unless
the vma is VM_NONLINEAR - one in which sys_remap_file_pages has been used
to place pages in unexpected places, to avoid an explosion of distinct
unmergable vmas.  Such pages were effectively locked in memory.

page_referenced_file is already skipping nonlinear vmas, they'd just waste
its time, and age unfairly any pages in their proper positions.  Now extend
try_to_unmap_file, to persuade it to swap from nonlinears.

Ignoring the page requested, try to unmap cluster of 32 neighbouring ptes
(in worst case all empty slots) in a nonlinear vma, then move on to the
next vma; stopping when we've unmapped at least as many maps as the
requested page had (vague guide of how hard to try), or have reached the
end.  With large sparse nonlinear vmas, this could take a long time:
inserted a cond_resched while no locks are held, unusual at this level but
I think okay, shrink_list does so.

Use vm_private_data a little like the old mm->swap_address, as a cursor
recording how far we got, so we don't attack the same ptes next time around
(earlier tried inserting an empty marker vma in the list, but that got
messy).  How well this will work on real- life nonlinear vmas remains to be
seen, but should work better than locking them all in memory, or swapping
everything out all the time.

Existing users of vm_private_data have either VM_RESERVED or VM_DONTEXPAND
set, both of which are in the VM_SPECIAL category where we never try to
merge vmas: so removed the vm_private_data test from is_mergeable_vma, so
we can still merge VM_NONLINEARs.  Of course, we could instead add another
field to vm_area_struct.

From: Hugh Dickins <hugh@veritas.com>

Dave McCracken's object-based reverse mapping scheme for file pages: why
build up and tear down chains of pte pointers for file pages, when
page->mapping has i_mmap and i_mmap_shared lists of all the vmas which
might contain that page, and it appears at one deterministic position
within the vma (unless vma is nonlinear - see next patch)?

Has some drawbacks: more work to locate the ptes from page_referenced and
try_to_unmap, especially if the i_mmap lists contain a lot of vmas covering
different ranges; has to down_trylock the i_shared_sem, and hope that
doesn't fail too often.  But attractive in that it uses less lowmem, and
shifts the rmap burden away from the hot paths, to swapout.

Hybrid scheme for the moment: carry on with pte_chains for anonymous pages,
that's unchanged; but file pages keep mapcount in the pte union of struct
page, where anonymous pages keep chain pointer or direct pte address: so
page_mapped(page) works on both.

Hugh massaged it a little: distinct page_add_file_rmap entry point; list
searches check rss so as not to waste time on mms fully swapped out; check
mapcount to terminate once all ptes have been found; and a WARN_ON if
page_referenced should have but couldn't find all the ptes.

Running __mark_inode_dirty() against a swapcache page is illegal and will
oops.

I see a race in set_page_dirty() wherein it can be called with a PageSwapCache
page, but if the page is removed from swapcache after
__set_page_dirty_nobuffers() drops tree_lock(), we have the situation where
PageSwapCache() is false, but local variable `mapping' points at swapcache.

Handle that by checking for non-null mapping->host.  We don't care about the
page state at this point - we're only interested in the inode.



There is a converse case: what if a page is added to swapcache as we are
running set_page_dirty() against it?

In this case the page gets its PG_dirty flag set but it is not tagged as dirty
in the swapper_space radix tree.  The swap writeout code will handle this OK
and test_clear_page_dirty()'s call to
radix_tree_tag_clear(PAGECACHE_TAG_DIRTY) will silently have no effect.  The
only downside is that future radix-tree-based writearound won't notice that
such pages are dirty and swap IO scheduling will be a teensy bit worse.


The patch also fixes the (silly) testing of local variable `mapping' to see if
the page was truncated.  We should test page_mapping() for that.

Revert recent changes to sync_page().  Now that page_mapping() returns
&swapper_space for swapcache pages we don't need to test for PageSwapCache in
sync_page().

Fix up the "may we call writepage" logic for the swapcache changes.

Go back to the 2.6.5 concepts, with rmap additions.  In particular:

- Implement Andrea's flavour of page_mapping().  This function opaquely does
  the right thing for pagecache pages, anon pages and for swapcache pages.

  The critical thing here is that page_mapping() returns &swapper_space for
  swapcache pages without actually requiring the storage at page->mapping. 
  This frees page->mapping for the anonmm/anonvma metadata.

- Andrea and Hugh placed the pagecache index of swapcache pages into
  page->private rather than page->index.  So add new page_index() function
  which hides this.

- Make swapper_space.set_page_dirty() again point at
  __set_page_dirty_buffers().  If we don't do that, a bare set_page_dirty()
  will fall through to __set_page_dirty_buffers(), which is silly.

  This way, __set_page_dirty_buffers() can continue to use page->mapping.
  It should never go near anon or swapcache pages.

- Give swapper_space a ->set_page_dirty address_space_operation method, so
  that set_page_dirty() will not fall through to __set_page_dirty_buffers()
  for swapcache pages.  That function is not set up to handle them.


The main effect of these changes is that swapcache pages are treated more
similarly to pagecache pages.  And we are again tagging swapcache pages as
dirty in their radix tree, which is a requirement if we later wish to
implement swapcache writearound based on tagged radix-tree walks.

Simplify the logic in there a bit.

->tree_lock is supposed to be IRQ-safe.  Hugh worked out that with his
changes, we never actually take it from interrupt context, so spin_lock() is
sufficient.

Apart from kinda freaking me out, the analysis which led to this decision
becomes untrue with later patches.  So make it irq-safe.

into ppc970.osdl.org:/home/torvalds/v2.6/linux

(The difference between two pointers is a "size_t", while
MAX_LEN and the result here are "int"s).

Forwarding table paranoia:
* Solve some potential problems if a device changes address and one or
  more device has the same address.  
* Warn if new device added to a bridge matches a entry that has shown
  up on the network.
* Also don't put static entries in the timer list, they don't time
  out so shouldn't be there.

Replacement 64 bit compatibility code for the new ioctl's.  The new 
ioctl's all pass through clean, but for the old style ioctl's it uses
the mis-feature of the earlier bridge-utils that they check the API version.

So if an old 32bit version of brctl is run on a 64bit platform it will
report
	bridge utilities not compatible with kernel version

Tested on Itanium 1; but should solve issue for sparc, ppc, and x86_64

Add four new ioctl's for the operations that can't be done through sysfs.
The existing bridge ioctl's are multiplexed, and most go through SIOCDEVPRIVATE
so they won't work in a mixed 32/64bit environment.

The new release of bridge-utils will use these if possible, and fall
back to the old interface.

Move the local function timer_residue to br_timer_value so it can
be used by both ioctl and sysfs code.

Change how the read of forwarding table works.  Instead of copying
entries to user one at a time, use an intermediate kernel buffer and
do up to a page at a chunk.

This gets rid of some awkward code dealing with entries getting deleted
during the copy.  And allows same function to be used by later sysfs
hook.

Fix a deadlock where deleting a device call br_del_if with lock held.
br_del_if doesn't want to be called under lock anymore.

Merge the ioctl stub calls that just end up calling the sub-function
to do the actual ioctl.  Move br_get_XXX_ifindices into the ioctl file
as well where they can be static.

Relax the locking on add/delete interfaces to a bridge.  Since these operations
are already called with RTNL semaphore, only need to hold the bridge lock while
doing operations related to STP and processing path.  This is necessary for later
sysfs support where those operations might sleep.

Minor cleanup (lead in to later sysfs support).  
Change new_nb to new_bridge_dev and return the net_device rather than
bridge because that is what the caller wants anyway.

This fixes the issue discovered when removing bluetooth devices from a bridge.
Need to add special case code when forwarding table is being cleaned up to 
handle the case where several devices share the same hardware address.

Also remove unused EOL define from ide.h.

This trivial patch makes grepping a lot easier.

- initializing needs to be set to 1 before calling ide_arm_init()

- ide_default_io_ctl() should be 0 on arm26

This driver was partially merged in 2.5.32 and never compiled in 2.5/2.6.
It was fixed in linux-mips CVS but has been broken again about 5 months ago.
Just remove it for now (it is in wrong directory anyway).

The patch below removes the MAINTAINERS entry for the removed comx
driver.

Additionally, the following comx header files could be removed:
  drivers/net/wan/mixcom.h
  drivers/net/wan/hscx.h
  drivers/net/wan/munich32x.h
  drivers/net/wan/falc-lh.h

I've double-checked that none of them are used by any other driver.

The case of CONFIG_JFFS2_FS_NAND=y got broken recently.

The bug is obvious, and the fix is trivial:

From: Ian Kent <raven@themaw.net>

This changes the autofs4 maintainer to me.  Recommended by Joe Perches and
OKed with Jeremy.

From: Ian Kent <raven@themaw.net>

This is a patch contributed by Joe Perches to automatically include the
function name in the dprintk statements.

From: Francois Romieu <romieu@fr.zoreil.com>

Missing cache size format for Intel P4E (p.26 of doc.  241618-025, "Intel
Processor Identification and the CPUID Instruction").

From: Armin Schindler <armin@melware.de>

Fixes a compiler warning about unused Eicon ISDN driver function if hotplug is
disabled.

From: Pavel Machek <pavel@ucw.cz>

This fixes bad interaction between devfs and swsusp.

Check whether the swap device is the specified resume device, irrespective of
whether they are specified by identical names.

(Thus, device inode aliasing is allowed.  You can say /dev/hda4 instead of
/dev/ide/host0/bus0/target0/lun0/part4 [if using devfs] and they'll be
considered the same device.  This is *necessary* for devfs, since the resume
code can only recognize the form /dev/hda4, but the suspend code would like
the long name [as shown in 'cat /proc/mounts'].)

[Thanks to devfs hero whose name I forgot.]

From: Pavel Machek <pavel@ucw.cz>

This is no longer neccessary.  We have enough pauses elsewhere, and it works
well enough that this is not needed.